Hey TT,
I'm afraid that the vast majority of countries would never allow individuals such as us to dig any treasure that they might class as 'cultural patrimony'. This would be the case regardless of how much work and effort had gone in by the individual.
They would soon find reason enough to get us out of the picture and where priceless artefacts of long-gone civilisations is concerned, I can understand why in view of what has gone on in the past.
Even in this age, there are numerous sites all over - if we are sticking to South America then I mean Peru in particular - where possible treasures are still buried awaiting discovery. Ironically, the value of gold and silver artefacts are not what they used to be and collectors now value exquisite textiles and pottery more due to demand. The only exception being outstanding pieces which are unique and expertly executed from certain groups over others.
To deepen the conundrum further, what if I told you I had the possible location of a burial site in the desert between northern Peru and south Ecuador which was dangerous territory due to drug traffickers?
What ethics and morals would be 'acceptable' in such an instance?
Do we tell the authorities and forget about the site?
Do we let local huaceros look and find and sell the artefacts for next to nothing?
Do we try and search ourselves with all the complex accumulaters involved?
It is my belief that there is several Mochica and Chimu sites still there, untouched, since the days of the Inca themselves....
With the question you pose about large amounts of money, there is a system in operation in South Asia called the "Havala", where a network of moneylenders, jewellers, traders and transient workers can send/receive funds based on promise and a handshake. It has been in operation for centuries. This is used to exchange literally hundreds of millions of dollars every year. I have seen trust-based meetings in Switzerland where deals have been made for hundreds of thousands of Swiss francs based on a nod and a nudge. Nothing untoward - just business deals.
It is mind-boggling and truly unbelievable unless you've seen it at source.
Maybe that is why I am so wanting to move on and enter this new career now....
IP